Experimental Study of the Periodic Vortex Shedding and Lock-in Region of an NACA4412 Airfoil
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Separated shear layer roll-up over the airfoil suction surface at post-stall incidences leads to harmonic vortex shedding and may damage the body structure if the shedding frequency gets locked into one of the natural frequencies of the body. This article presents the results of a series of wind tunnel tests carried out on a stationary and oscillatory NACA4412 airfoil at an angle of attack (AOA) of 45° and Reynolds numbers Re=1.34×105 and Re=1.52×105 to perform an in-depth investigation of the vortex shedding and lock-in region for an oscillating airfoil in the low subsonic flow regime. Resulting from the semisinusoidal forced pitching motion, the lock-in region in the oscillation’s frequency-amplitude plane was V-shaped, where the vortices shed with the oscillation frequency (lock-in condition) inside the V boundaries. Outside the V boundaries (unlocked conditions), the random shedding of vortices and their interaction causes the kinetic energy scattering in the frequency band limited to the oscillation frequency and the frequency associated with the quasi-steady condition due to the mean angle of attack. Moreover, the aerodynamic damping was examined by calculating the net energy transfer between the body and flow indicated that the direction of the energy transfer between the airfoil’s body and flow is a function of both the oscillation amplitude and frequency, except during oscillation with the resonant frequency at which energy is always transferred from flow to the body.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it